1. Field of the Invention
The present invention relates to an improvement in a rotative toothbrush which brush the teeth vertically up and down as well as horizontally right and left. The effective way of brushing the teeth is to brush the teeth vertically up and down as well as horizontally right and left. The present invention is concerned with the improvement of a rotative toothbrush which automatically moves up and down when the user brushes the teeth horizontally right and left in a conventional way.
2. Description of the Prior Arts
A toothbrush most generally used is illustrated in FIG. 8. Since a human mouth is opened horizontally, it is most convenient to brush the teeth horizontally right and left.
For a long time, human beings have brushed their teeth horizontally right and left with the conventional toothbrush shown in FIG. 9. However, since such brushing of the teeth is carried out horizontally right and left, food particles and plaques existing between the teeth are not removed well.
Moreover, the teeth themselves (are worn) out horizontally by the conventional brushing of the teeth and therefore, one or more grooves near the toothridges are formed by a conventional, long brushing of the teeth.
Therefore, dentists advise that the user brushes the teeth vertically up and down. However, such vertical brushing of the teeth is not familiar to the common users and accordingly, the vertical brushing of teeth using the conventional toothbrush is very inconvenient. In order to solve these problems, U.S. Pat. No. 4,783,869 describes a toothbrush shown in FIG. 9. However, the toothbrush shown in the U.S. Pat. No. 4,783,869 does not rotate completely and the slight rotative movement forms an angle between the teeth and the toothbrush as described in the same U.S. Patent. Thus, effect of such brushing is insufficient and inadequate because as shown in FIG. 11, only a small portion of the brushhair of the brushhead contacts the teeth when the user uses the toothbrush.
The present inventor invented a rotative toothbrush as shown in FIG. 10 which the center of a round brushead is connected with the grip by the shaft, and was filed in a Korean utility model application as No. 87-19458 (Unexamined Utility Model Publication No. 89-10102). However, as the rotative shaft is located at the center of the brushhead and as the friction (power) between the brushhairs of the brushhead and the teeth are the same in all directions, the brushhead does not rotate well. Accordingly, the effect of vertical brushing of the teeth is not, in fact, obtained. The present inventor invented the present invention as a result of an intensive study.